Credit: AP

When the Tigers made Miller the sixth pick in the 2006 draft, they did so in hoping to acquire the next Big Unit. Miller’s stuff made comparisons not completely baseless — the 98 mph fastball from the left side, the wipeout slider from a 6-foot-7 frame.

But he lacked command and soon he lacked confidence, too, the result of an ill-advised promotion to the majors just months after the draft. He bounced from Detroit to Florida to Boston, posting an ERA of 5.70 in 66 starts.

A funny thing happened to Miller on the road to irrelevance, though. The Red Sox turned him into a reliever, and Miller responded with the kind of numbers that would look right at home on the back of Johnson’s baseball card.

Miller entered yesterday’s game against the Orioles averaging 15.0 strikeouts per nine innings. That’s the second-highest ratio in the major leagues among pitchers with at least 23 innings, trailing only dynamic Reds closer Aroldis Chapman, who’s at 15.6.

Using those same criteria (and it is an admittedly low number of innings), it’s also the highest rate in Red Sox history, ahead of Pedro Martinez’ otherworldly 1999, when he struck out 313 in 2131⁄3 innings (13.2/9 IP), and also ahead of great seasons from the likes of Jonathan Papelbon, Dick Radatz and Lee Smith.

“It’s remarkable,” teammate Craig Breslow said. “His stuff is elite. He’s immensely talented and it’s all kind of coming together. To start making judgments a third of the way through the season is premature, but there’s no reason to be surprised that a 6-7 lefty throwing 98 mph with a devastating slider should be able to strike guys out pretty consistently.”

What’s perhaps most surprising is the way Miller has locked down right-handed hitters. Righties posted an .829 OPS against him last year, but that number has plummeted to .511 with a .128 average this season. He has recorded 19 of his 39 Ks in 231⁄3 innings against them as well, consistently burying his slider inside.

Saltalamacchia feigned indignation when asked about Miller’s success.

“He’s very high-maintenance,” he joked. “He’s got two pitches and he’s paranoid guys are going to pick up signs. It’s like, ‘Dude, you throw 97 with a slider that’s filthy. Just throw it.’ You could tell them what’s coming and they still wouldn’t hit it.”

Saltalamacchia turned more serious.

“As a hitter, when a guy throws that hard and has all legs and elbows and everything coming at you, it’s hard enough to hit,” he said. “But when he starts hitting the corners, it’s even tougher.”

The move to the bullpen has clearly helped. Miller no longer worries about expanding his arsenal or being perfectly efficient.

“As a reliever, I’m not saving my breaking ball for the third time I see Chris Davis,” Miller said. “Starters have to worry about pitch counts. The difference between me throwing 14 and 18 pitches isn’t a big deal. What’s an extra four pitches an inning for me? For a starter, that’s the difference between being an All-Star and a fringe guy.”

Which brings us back to Johnson. Miller’s not the Hall of Fame left-hander, but for one-inning stints, he can do a pretty decent impression, especially when it comes to strikeouts.

“Obviously, I’m not the kind of pitcher he was, but any sort of comparison is a huge compliment,” Miller said. “I can see it with the height thing, although he has a few inches on me and certainly a few miles per hour. I’ll take any comparison I can get, but ultimately I’ve got to be myself and get outs however I can.”